Survival estimates of GPS-tagged adult Golden Eagles (Aquila chrysaetos) breeding in Finland

Abstract

Adult survival estimates are important for assessing population status and viability and for investigating the role of different anthropogenic effects on their variation. Currently, the rapidly increasing wind power poses a new and severe threat to survival of large raptors. Between 2011–2024, we monitored 26 Golden eagles (Aquila chrysaetos) using Global Positioning System tracking devices in Finland, on territories where wind-power plants are currently absent and eagles are not subject to increased mortality from wind power plant collisions. Using the accumulated tracking data, we constructed individual capture histories on a monthly basis and adult survival rates using known-fate models in program MARK. We also review published adult survival estimates of Golden Eagles reported throughout their range for relative comparison. Monthly adult survival in our study area was 0.9933 (0.9854–0.9970) which translates to annual survival of 0.924 (0.838–0.965). We found eight studies reporting survival estimates, which ranged from 0.860 to 0.975 with a mean of 0.928. Thus, adult survival rates of Golden Eagles breeding in northern Finland, that are not affected by wind power plants, are high as expected for a viable population and very close to the mean estimated from other Golden Eagle populations. Maintaining high adult survival rates will be key to Golden Eagle population stability with expanding wind energy development in Finland.